Electric motor and electric pump

ABSTRACT

An electric pump has a pump body, a pump magnet received in the pump body, an impeller received in the pump body and fixed to the pump magnet, and a disc type electric motor. The electric motor includes a stator, disc type coils fixed to a surface of the stator, a rotor rotatably positioned above the coils, and a circuit board electrically connected to the coils. The rotor has a rotor magnet positioned beneath the pump body and magnetically coupled to the pump magnet. When the coils are energized, an axial magnetic field is generated to drive the rotor and, through the magnetic coupling between the rotor magnet and the pump magnet, rotate the impeller.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201510253238.X filed in The People's Republic of China on May 18, 2015, the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to an electric pump, and in particular, to an electric pump having a disc type electric motor and to a disc type electric motor.

BACKGROUND OF THE INVENTION

Electric pumps for home appliances, such as dish washing machines, generally adopt a direct current electric motor with a radial gap or an induction motor with a radial gap. However, these electric motors have a comparatively long axial dimension and a complicated structure.

SUMMARY OF THE INVENTION

Hence there is a desire for an electric pump having a short axial dimension.

Accordingly, in one aspect thereof, the present invention provides an electric pump, comprising: a pump body; a pump magnet rotatably disposed in the pump body; an impeller disposed in the pump body and fixed to the pump magnet; and a disc type electric motor positioned beneath the pump body for rotating the magnet and the impeller, the disc type electric motor comprising a stator and a rotor, the stator comprising: a stator core, a number of disc type coils fixed to a surface of the stator core, and a circuit board positioned on an end of the stator and electrically connected to the disc type coils, the rotor comprising a rotor magnet positioned between the disc type coils and the pump body, the magnet being positioned confronting the pump magnet to produce a magnetic coupling between the rotor magnet and the pump magnet, wherein when electrical power is applied to the circuit board, the disc type coils generate an axial magnetic field to drive the rotor, thereby rotating the pump magnet and the impeller.

Preferably, a plurality of fasteners secure the disc type electric motor to the pump body.

Preferably, spaced tabs extend radially from the stator, each tab has a through hole, the fasteners engage the through holes to secure the disc type electric motor to the pump body.

Preferably, an iron sheet is fixed to the pump magnet, providing a flux return path.

According to a second aspect, the present invention provides a disc type electric motor, having a stator and a rotor, the stator comprising: a stator core; a number of disc type coils fixed to a surface of the stator core; a circuit board positioned on an end of the stator core and electrically connected to the disc type coils, the rotor rotatably positioned above the disc type coils and comprising a rotor magnet; and wherein when the circuit board is energized, the disc type coils generate an axial magnetic field to rotate the rotor.

Preferably, the stator has a plurality of grooves and through holes through which ends of windings of the disc type coils pass.

Preferably, the stator core has a plurality of first through holes arranged in the circumferential direction, through which the windings of the disc type coils pass to reach a lower surface of the stator core.

Preferably, the motor comprises a plurality of bobbins, a plurality of positioning members, and a plurality of second through holes formed in the stator core and arranged in the circumferential direction, wherein the disc type coils are wound around the bobbins, each bobbin defines a third through hole, and each positioning member extends through a respective third through hole and a respective second through hole to secure a respective bobbin to the stator core.

Preferably, the rotor magnet is annular with a plurality of grooves formed in a radially inner surface and spaced in the circumferential direction, a solid glue is applied to the grooves to secure the rotor magnet to a shaft of the rotor.

Preferably, the disc type electric motor further comprises a solid glue layer, the solid glue layer is applied on an lower surface of the stator core and covers exposed parts of the windings of the coils.

According to a third aspect, the present invention provides an electric pump, comprising: a pump body; a pump magnet received in the pump body; an impeller received in the pump body and fixed to the pump magnet; a disc type electric motor for rotating the pump magnet and the impeller; and an iron sheet fixed between the pump magnet and the impeller.

According to a fourth aspect, the present invention provides an electric pump, comprising: a pump body; an impeller received in the pump body; an electric motor for driving the impeller, wherein the electric motor is a disc type electric motor and drives the impeller through a magnetic coupling.

Preferably, a pump magnet is fixed to the impeller within the pump body; and an iron sheet is fixed between the pump magnet and the impeller.

Preferably, the disc type electric motor is an electric motor as defined in the second aspect above.

Advantages of the present invention include providing an electric pump with short axial dimension, which meets the trend of miniaturization of home appliances. Further advantages of specific embodiments may be understood from the description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.

FIG. 1 is a schematic view of an electric pump in accordance with a preferred embodiment of the invention;

FIG. 2 is a sectional view of the electric pump of FIG. 1;

FIG. 3 is a view of an electric motor, being a part of the pump of FIG. 1;

FIG. 4 is a view of an electric motor according to a second embodiment;

FIG. 5 illustrates the electric motor of FIG. 4, with a rotor removed; and

FIG. 6 illustrates the electric motor of FIG. 3 or 4, viewed from another aspect.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic view of an electric pump 1 in accordance with a preferred embodiment of the invention. FIG. 2 is a sectional view of the pump. The pump 1 includes a pump body 10, a pump magnet 14 disposed in the pump body 10, an impeller 11 disposed in the pump body 10 and fixed with the pump magnet 14, and a disc type electric motor 20 for rotating the pump magnet 14 and the impeller 11 within the pump body 10. In this embodiment, the disc type electric motor 20 is a brushless electric motor. In other embodiments, the disc type electric motor 20 may be a brush type electric motor.

In this embodiment, the pump magnet 14 and the impeller 11 are rotatably fixed to an inner surface of a bottom of the pump body 10 via a spindle 12 and a bearing (not shown), such that the impeller and pump magnet are able to rotate about the axis of the spindle within the pump body 10. The spindle 12 may or may not be rotatable. The pump 10 includes a water inlet 110 and a water outlet 111.

As shown in FIG. 3, the disc type electric motor 20 includes a rotor 21 and a stator 25. The stator includes a stator core 255 and a number of disc type coils 24 fixed to a surface of the stator core 255. A circuit board 23 is fixed to the stator core 255 and is electrically connected to the disc type coils 24. The rotor 21 is positioned above the disc type coils 24, and is rotatably connected to the stator 25 via a shaft 27 and a bearing 250. In this embodiment, the rotor 21 has a rotor magnet 212. When the circuit board 23 is connected to an external power source and is powered on, the coils 24 are energized and generate an axial magnetic field, that causes the rotor 21 to rotate. In this embodiment, the rotor 21 is disc shaped and the stator core 255 is a flat plate. The stator 25 and the circuit board 23 may be integrally formed.

A plurality of spaced tabs 26 extend outwardly in a radial direction from the stator. Each tab 26 has a through hole 22. The motor 20 is fixed to an external surface of a bottom of the pump body 10 by a plurality of fasteners 30 (as shown in FIG. 2) engaging in the through holes 22 of the tabs 26. In this embodiment, the fasteners 30 are screws. Three tabs 26 and fasteners 30 are used in this embodiment but the number may vary according to need. In other embodiments, the fastener 30 may be fixed to the external surface of the bottom of the pump body 10 by other means, such as welding.

As shown in FIG. 4, the rotor magnet 212 is annular. A radially inner circumferential surface of the rotor magnet has a number of interleaved protrusions 210 and grooves 211. Solid glue 213 is applied into the groove 211 to secure the shaft 27 to a middle of the rotor magnet 212. The protrusions 210 are configured to generate a relative larger surface area for the glue to bond to the rotor magnet. In this embodiment, the main gradient of the solid glue is epoxy resin.

As shown in FIG. 5 and FIG. 6, a plurality of spaced grooves 253 are defined at a radial outer surface of the stator 25. An end of the windings of the coils 24 extends through a respective groove 253 to a lower surface of the stator core.

As shown in FIG. 6, the stator 25 has a plurality of first through holes 251 and a plurality of second through holes 252 arranged in the circumferential direction. A circle on which the first through holes 251 are located and a circle on which the second through holes are located are concentric.

The first through holes 251 allow the other end of the windings of the disc type coils 24 to pass through the stator core 255. The disc type electric motor 20 further includes a plurality of bobbins 29 and a plurality of positioning members 291. Each bobbin 29 defines a third through hole 290. Each positioning member 291 extends through a third through hole 290 and a second through hole 252 to secure the corresponding bobbin 29 to the surface of the stator 25. Each coil 24 is wound around a respective bobbin 29. In this embodiment, each bobbin 29 has a trapezoidal shape. Alternatively, the positioning members may be integrally formed with the bobbins.

The disc type electric motor 20 further includes a solid glue 28. The solid glue 28 is applied on the lower surface of the stator 25, the outer surface of the stator 25 and those parts of the disc type coil 24 that are exposed to air, thereby completely isolating the windings of the coils 24 from the external environment, reducing potential damage to the disc type coil 24.

Furthermore, the electric pump 1 includes an iron sheet 13 fixed above the pump magnet 14. The iron sheet 13 provides a magnetic flux return path, to enhance the magnetic field intensity.

When the electric pump 1 is used, electrical power is supplied to the circuit board 23, energizing the coils 24 to generate an axial magnetic field. The axial magnetic field drives the rotor 21. Rotation of the rotor 21 drives the pump magnet 14 in the pump body 10 causing the impeller 11 to rotate. At the same time, the iron sheet 13 fixed above the pump magnet 14, forms a magnetic flux return path, thereby enhancing the magnetic field intensity, and forming a better magnetic connection between the rotor magnet and the pump magnet, through which the rotor 21 drives the impeller 11.

Further, the rotor of the disc type electric motor 20 is not physically connected to the pump magnet 14 in the pump body 10 via a spindle or shaft, and does not extend into an inside of the pump body. Rather, the rotor of the disc type electric motor 20 and the impeller 11 are located on opposite sides of a continuous bottom wall portion of the pump. Thus the motor is isolated from the working fluid of the pump and there are no seals that may fail leading to leakage of liquid from the pump and/or failure of the motor.

In this embodiment of the invention, by adopting the disc type electric motor, the height of the pump can be kept small while eliminating the need for shaft seals and the like.

In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of example only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims. 

1. An electric pump, comprising: a pump body; a pump magnet rotatably disposed in the pump body; an impeller disposed in the pump body and fixed to the pump magnet; and a disc type electric motor positioned beneath the pump body for rotating the magnet and the impeller, the disc type electric motor comprising a stator and a rotor, the stator comprising: a stator core, a number of disc type coils fixed to a surface of the stator core, and a circuit board positioned on an end of the stator and electrically connected to the disc type coils, the rotor comprising a rotor magnet positioned between the disc type coils and the pump body, the magnet being positioned confronting the pump magnet to produce a magnetic coupling between the rotor magnet and the pump magnet, wherein when electrical power is applied to the circuit board, the disc type coils generate an axial magnetic field to drive the rotor, thereby rotating the pump magnet and the impeller.
 2. The electric pump of claim 1, further comprising a plurality of fasteners securing the disc type electric motor to the pump body.
 3. The electric pump of claim 2, wherein spaced tabs extend radially from the stator, each tab has a through hole, the fasteners engage the through holes to secure the disc type electric motor to the pump body.
 4. The electric pump of claim 1, further comprising an iron sheet fixed to the pump magnet, providing a flux return path.
 5. A disc type electric motor, having a stator and a rotor, the stator comprising: a stator core; a number of disc type coils fixed to a surface of the stator core; a circuit board positioned on an end of the stator core and electrically connected to the disc type coils, the rotor rotatably positioned above the disc type coils and comprising a rotor magnet; and wherein when the circuit board is energized, the disc type coils generate an axial magnetic field to rotate the rotor.
 6. The motor of claim 5, wherein the stator has a plurality of grooves and through holes through which ends of windings of the disc type coils pass.
 7. The motor of claim 5, wherein the stator core has a plurality of first through holes arranged in the circumferential direction, through which the windings of the disc type coils pass to reach a lower surface of the stator core.
 8. The motor of claim 5, further comprising a plurality of bobbins, a plurality of positioning members, and a plurality of second through holes formed in the stator core and arranged in the circumferential direction, wherein the disc type coils are wound around the bobbins, each bobbin defines a third through hole, and each positioning member extends through a respective third through hole and a respective second through hole to secure a respective bobbin to the stator core.
 9. The motor of claim 5, wherein the rotor magnet is annular with a plurality of grooves formed in a radially inner surface and spaced in the circumferential direction, a solid glue is applied to the grooves to secure the rotor magnet to a shaft of the rotor.
 10. The motor of claim 5, wherein the disc type electric motor further comprises a solid glue layer, the solid glue layer is applied on an lower surface of the stator core and covers exposed parts of the windings of the coils.
 11. An electric pump, comprising: a pump body; a pump magnet received in the pump body; an impeller received in the pump body and fixed to the pump magnet; a disc type electric motor for rotating the pump magnet and the impeller; and an iron sheet fixed between the pump magnet and the impeller.
 12. The pump of claim 11, wherein the disc type electric motor has a stator and a rotor, the stator comprising: a stator core; a number of disc type coils fixed to a surface of the stator core; a circuit board positioned on an end of the stator core and electrically connected to the disc type coils, the rotor comprising a rotor magnet rotatably positioned above the disc type coils; and wherein when the circuit board is energized, the disc type coils generate an axial magnetic field to rotate the rotor. 